Expansion anchor



A. FISCHER EXPANSION ANCHOR Sept. 12, 1967 2 Sheets-Sheet 1 Filed June 14, 1965 INVENTOR.

ARTUR FISCHER Sept. 12, 1967 A. FISCHER EXPANSION ANCHOR 2 Sheets-Sheet Filed June 14, 1965 Fig.

INVENTOR. ARTUR FISCHER,

United States Patent 7 Claims. (in. 85-71) The present invention concerns an anchoring means. More specifically, the present invention concerns an anchoring means of the expansion type. Still more specifically it concerns an expansion anchor which is variable in its overall length.

Expansion anchors of the type insertable in a bore or the like provided in masonry or other walls, and which is then radially expanded so as to frictionally engage the circumferential wall of the bore, are well known. However, with all such expansion anchors it is necessary to carefully select the length of the anchor sleeve and of the means, generally a screw, used for expanding it. If, now, circumstances dictate the use of a screw longer than the sleeve of the expansion anchor, then it frequently occurred that the threaded portion of the screw passed beyond the complementary threaded portion of the sleeve and the screwand with it the element to be secured by it-was no longer reliably held in the expansion anchor sleeve.

It is an object of the present invention to overcome the above-mentioned shortcomings of prior-art constructions.

Another object of the invention is to provide an ex pansion anchor whose axial length is selectively variable.

Still a further object is to provide an exapnsion anchor of the type described which is simple and economical to manufacture.

In accordance with one feature of my invention I provide, in an expansion anchor, an elongated sleeve having an annular first end portion, a slotted second end portion defining a plurality of tongues and being expandable in response to internal expanding stresses, an intermediate portion between said first and second end portions, and a weakened portion between said first end portion and said intermediate portion, said weakened portion being adapted to buckle outwardly in response to axial compressive stresses, and a combined expanding and shortening member adapted to initially expand said second end portion and to subsequently exert axial compressive stresses on said weakened portion whereby said weakened portion will buckle outwardly and the overall length of said sleeve will thereby be reduced.

The objects of the invention are achieved by providing the elongated sleeve, which is preferably made from a resilient plastic material, such as a slow-aging polyamide, with an end portion which is insertable into a bore in a wall or the like, and a free end portionvwhich will be located outside the bore. The end portion which is located outside the bore is axially slotted so that, when a screw shorter than the sleeve is being used, rotation of the screw in a sense which tends to insert the same deeper into the elongated sleeve, will cause axial compressive stresses to be brought to bear on the free end portion so that the same will buckle outwardly and thereby reduce the overall length of the sleeve. It will be seen that a short screw,

which would usually be unable to properly engage the screw-threads of the sleeve, is now able to do so since the weakened portion of the sleeve will yield, thereby permitting deeper entry of the screw. On the other hand, a longer screw will be able to engage the screw-threaded portion of the sleeve before the screw-head exertsaxial compressive stresses on the weakened portion of the sleeve, so that buckling of the weakened portion need not, and will not, take place. The expansion anchor according to the present invention thus is capable of automatically adapting itself to various screw lengths.

Since the outer free end portion of the sleeve is preferably formed with a flange extending transversely of the direction of elongation of the sleeve, the inventive expansion anchor can also be used to secure corrugated covering materials, such as corrugated sheet materials, to a wall or a roof. It is essential that such materials do not leak and sealing of the openings for the fastening means used has always presented a problem. With the inventive construction the opening through which the expansion anchor sleeve is inserted in these corrugated materials is reliably sealed by tight engagement of the flange of the sleeve with the material.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompany drawings, in which:

FIG. 1 is a partly sectioned elevational view of an expansion anchor of the present invention, used to secure a corrugated material having a steep pitch of corrugation to a wall;

FIG. 2 is a view substantially similar to that of FIG. 1 and shows the inventive expansion anchor in use with a corrugated material having a lesser pitch of corrugation; and

FIG. 3 is a partially sectioned elevational view of a portion of the inventive anchor showing how the flange of the sleeve acts as a seal for the inserting opening.

As is evident from FIG. 1 the elongated sleeve 1 is formed with an inner end portion 1a adapted to be inserted into a bore in a wall or the like. The outer end, that is that end which will remain outside the bore, of the sleeve 1 is formed with a weakened portion 2. The inner end portion 1a is axially slotted as indicated by reference numeral 3, these slots extending toward but short of the weakened portion 2. The latter is also axially slotted toward but short of the inner portion 1a. The formation of slots 3a in the portion 2 creates a plurality of elongated ribs 2a (see FIG. 2). Outwardly of the portion 2 the sleeve is formed adjacent its free end with an annular free end portion 4 and in turn this end portion 4 is formed with a flange 5 extending transversely of the direction of elongation of sleeve 1. As shown in FIG. 3 the flange 5 will act as a sealing element to reliably prevent the entry of moisture through the insertion opening through which sleeve 1 extends.

Sleeve 1 is inserted into a bore 8 formed in a wall or the like 9. The sleeve shown in FIG. 1 serves to secure a corrugated member 6 having a relatively steep pitch of corrugation to the wall 9. For this purpose the sleeve 1 is inserted through an opening 6 formed in the member 6 and extends into the bore 8 of wall 9. In view of the relatively pronounced pitch of the corrugation of member 6 a correspondingly long screw 7a is inserted into the sleeve 1. The screw 7 is then rotated in a threadengaging sense until its head 7 engages the flange 5 of sleeve 1. During this rotation of screw 7 its forward end expands the inner end portion 1a of sleeve 1 and presses the fastening means, such as the tongues 10, 11 of the inner end portion, into engagement with the wall of the bore 8. The member 6 is now reliably secured to the wall.

If, now, a shorter screw is to be used with the sleeve 1, as is occasioned in FIG. 2 by the fact that the corrugations of the member 6a are less steep than those of member 6 shown in FIG. 1, the axial length of the sleeve 1 is excessive and requires adjustment. This is accomplished by simply rotating the screw 7b in a thread-em gaging sense until the head 7 of screw 7b engages the flange 5' of sleeve 1, on which it will exert axial compressive stresses so that the resilient ribs 2a of portion 2 are caused to buckle outwardly in their attempt to yield to these stresses. The axial length over-all of sleeve 1 will thus be reduced exactly by that amount by which the sleeve is too long, since obviously the axial stress will be relieved and continued outward buckling will be terminated, when the head 7 of screw 7b has displaced the flange 5 into engagement with the outer surface of the corrugated member 6a.

As has already been indicated before, the transverse flange 5 of sleeve 1 serves as a sealing element to seal the opening through which the expansion anchor sleeve is inserted. This is shown in FIG. 3 from which it will be plain that the head of screw 7 will so displace the flange 5 into contact with the underlying material that a tight seal is established.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of expansion anchor differing from the types described above.

While the invention has been illustrated and described as embodied in expansion anchors, it is not intended to be limited to the details shown, since various modi fications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an expansion anchor, an elongated sleeve having a peripherally continuous annular end portion at one end of said sleeve, a slotted second end portion at the other end of said sleeve defining a plurality of tongues and being expandable in response to internal expanding stresses, a peripherally continuous intermediate portion located adjacent to said second end portion but spaced from said first end portion, and a longitudinally extending weakened portion located between said first end portion and said intermediate portion, said weakened portion being adapted to buckle outwardly in response to axial compressive stresses whereby, when such stresses are exerted on said sleeve, said weakened portion will buckle outwardly and the overall length of said sleeve will thereby be reduced.

2. A structure as defined in claim 1, wherein said sleeve consists of resilient synthetic plastic material.

3. A structure as defined in claim 1, wherein said weakened portion is slotted in longitudinal direction so as to define elongated ribs.

4. A structure as defined in claim 1, and further com prising a combined expanding and shortening member cooperating with said sleeve and adapted to initially expand said second end portion and subsequently to exert axial compressive stresses on said weakened portion.

5. A structure as defined in claim 4, wherein said peripherally'continuous annular end portion is provided 1 with a flange extending transversely of the elongation of said sleeve; said combined expanding and shortening member having a head adapted to engage said flange subsequently to expansion of said second end portion by said member, and to exert said axial compressive stresses on said flange and thereby on said weakened portion.

6. A structure as defined in claim 5, said combined expanding and shortening member further having a stem integral with said head and adapted to extend through said sleeve and to engage said intermediate portion, said stem having a terminal portion spaced from said head and adapted to initially expand said slotted second end portion prior to engagement of said flange by said head.

7. A structure as defined in claim 6, wherein said intermediate portion of said sleeve is internally screwthreaded and said stem is peripherally screw-threaded,

expansion of said slotted second end portion and outward buckling of said weakened portion taking place in response to rotation of said combined expanding and shortening member in a sense tending to mesh said screw threads and to introduce said member deeper into said sleeve.

References Cited UNITED STATES PATENTS 1,878,600 9/1932 Pleister 85-71 3,171,321 3/1965 Fischer 8583 3,191,730 6/1965 Fischer 855O FOREIGN PATENTS 1,278,641 11/1961 France.

CARL W. TOMLIN, Primary Examiner.

R. S. BRITTS, Assistant Examiner. 

1. IN AN EXPANSION ANCHOR, AN ELONGATED SLEEVE HAVING A PERIPHERALLY CONTINUOUS ANNULAR END PORTION AT ONE END OF SAID SLEEVE, A SLOTTED SECOND END PORTION AT THE OTHER END OF SAID SLEEVE DEFINING A PLURALITY OF TONGUES AND BEING EXPANDABLE IN RESPONSE TO INTERNAL EXPANDING STRESSES, A PERIPHERALLY CONTINUOUS INTERMEDIATE PORTION LOCATED ADJACENT TO SAID SECOND END PORTION BUT SPACED FROM SAID FIRST END PORTION, AND A LONGITUDINALLY EXTENDING WEAKENED PORTION LOCATED BETWEEN SAID FIRST END PORTION AND SAID INTERMEDIATE PORTION, SAID WEAKENED PORTION BEING ADAPTED TO BUCKLE OUTWARDLY IN RESPONSE TO AXIAL COMPRESSIVE STRESSES WHEREBY, WHEN SUCH STRESSES ARE EXERTED ON SAID SLEEVE, SAID WEAKENED PORTION WILL BUCKLE OUTWARDLY AND THE OVERALL LENGTH OF SAID SLEEVE WILL THEREBY BE REDUCED. 